Delete Model;

// hexa elements
// 4 along length , 1 along width z, 1 along height y
size = 480/4;
Point (1) = {0, 0, 0, size};
Point (2) = {0, 0, 30, size};
Line (1) = {1, 2};
Extrude {0, 30, 0} { Line{1}; Layers {{1}, {1} }; }

Transfinite Surface {5} Right;

// 4 layers of 1 element
Extrude {480, 0, 0} { Surface{5}; Layers { {1, 1, 1, 1}, {0.25, 0.5, 0.75, 1} } ;}
Transfinite Line "*" = 2;

Transfinite Surface "*" Right;

Recombine Surface "*" =0 ;
Transfinite Volume "*" ;
Mesh 1;
Mesh 2;

